Hydraulic compositions used in the fields of civil engineering, architecture, and the like contain hydraulic powder and water. As hydraulic powder, exemplified are portland cement (JIS R 5210), blast furnace cement (JIS R 5211), silica cement (JIS R 5212), fly ash cement (JIS R 5213), alumina cement and others. As quality standards for cement, the strength classes are classified in terms of the strength (for example, three ranks for 28-day strength and two ranks for early strength) as in Europe or China. However, in any case, cement is contained as a main component of hydraulic powder. One of the reasons therefor is to ensure the strength required for removal from a formwork after hardening, especially 3-day strength expressed as the early strength.
JP-A 61-117142 discloses, as a cement composition with a hardening acceleration property, a cement composition containing sodium hydroxymethanesulfonate and sodium thiocyanate.
In the meantime, in the steel industry, a substance, which contains a mineral component separated by melting from metals for metallurgy, is generated as a by-product during iron smelting from an ore. This substance is called slag. Conventionally, slag has been actively used as a part of raw materials or products mainly in the field of building materials. In particular, in the field of cement, it is used not only as a raw material but also as a product or an admixture blended in cement.
However, although slag is a mineral having a latent hydraulic property, it hardly exhibits an early strength of the level of three days. Therefore, in order to exhibit a high early strength, a formulation amount of cement, an improvement of degree of fineness or the like is adjusted.
JP-A 2013-517202 discloses, as an alkali activation binder not containing cement, mortar or concrete containing a composite activator composed of slag, an alkaline hydroxide and a carbonate.